System and method using a rate split scheme based on cooperation between receivers

ABSTRACT

Each of a first transmitter and a second transmitter uses a rate split scheme. Each of the first transmitter and the second transmitter may transmit at least four sub-messages, and different transmission powers may be allocated to the at least four sub-messages. Also, each of receivers may cooperate with each other, may share sub-messages that act as interferences, and may extract desired messages using the shared sub-messages.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/830,261, filed on Jul. 2, 2010, which claims the benefit under 35U.S.C. §119(e) of U.S. Provisional Application No. 61/291,525, filed onDec. 31, 2009, in the U.S. Patent and Trademark Office, and claims thebenefit under 35 U.S.C. §119(a) of Korean Patent Application No.10-2010-0001162, filed on Jan. 7, 2010, in the Korean IntellectualProperty Office, the entire disclosure of each of which is incorporatedherein by reference for all purposes.

BACKGROUND

1. Field

The following description relates to a communication system and acommunication method that use a rate split scheme.

21 . Description of Related Art

There are a variety of methods for processing/eliminating interferencein a wireless communication system and a variety of methods forimproving the capacity of the communication system in an environmentwhere an interference channel exists.

For example, when the strength of an interference signal is weak, areceiver may regard the interference as a noise and may decode areceived signal to extract a desired signal. Conversely, when thestrength of the interference signal is strong, the receiver may decodethe interference first, eliminate the interference from the receivedsignal, and subsequently extract a desired signal.

When the strength of the interference signal is moderate, a method knownas a Han-Kobayashi may be used to remove interference. According to theHan-Kobayashi method, a transmitter may split a transmission messageinto a common message and a private message. The transmitter may apply asuperposition-coding to the common message and the private message, andmay transmit the superposition-coded message. The transmitter may behave a corresponding receiver, and the common message refers to amessage that is decodable in an adjacent receiver in addition to thereceiver corresponding to the transmitter. The private message is amessage that is decodable only in the receiver corresponding to thetransmitter. A scheme of splitting the transmission message into atleast two messages and then allocating different rates or differenttransmission powers to the at least two messages, is generally referredto as a rate split scheme.

SUMMARY

In one general aspect, there is provided a communication method of atransmitter, the method comprising: generating a transmission messagecomprising: a 1-1-(i−1)^(th) sub-message; a 2-1-(i−1)^(th) sub-message;a 2-1-(i)^(th) sub-message; and a 3-1-(i−1)^(th) sub-message in a(i−1)^(th) time slot; allocating transmission powers A, B, C, and D [W],respectively, in the transmission message of the (i−1)^(th) time slot,A, B, C, and D denoting real numbers and A>B>C>D, to: the 1-1-(i−1)^(th)sub-message; the 2-1-(i−1)^(th) sub-message; the 2-1-(i)^(th)sub-message; and the 3-1-(i−1)^(th) sub-message; and generating atransmission message comprising the 2-1-(i)^(th) sub-message in a(i)^(th) time slot.

The method may further include allocating a transmission power B to the2-1-(i)^(th) sub-message in the transmission message in the (i)^(th)time slot.

The method may further include determining the transmission powers A, B,C, and D based on information associated with an interference channel ofa corresponding transmission/reception pair and information associatedwith an interference channel of an adjacent transmission/reception pair.

The method may further include: cooperating with the adjacenttransmission/reception pair; and collecting information associated withthe interference channels.

The method may further include that the allocating allocates thetransmission powers A, B, C, and D, respectively, to enable a receiverof the adjacent transmission/reception pair to: succeed in decoding ofthe 1-1-(i−1)^(th) sub-message and the 2-1-(i−1)^(th) sub-message fromthe transmission message in the (i−1)^(th) time slot; and fail indecoding of the 2-1-(1)^(th) sub-message and the 3-1-(i−1)^(th)sub-message from the transmission message in the (i−1)^(th) time slot.

The method may further include that the allocating allocates thetransmission powers A, B, C, and D, respectively, to enable a receivercorresponding to the transmitter to succeed-in decoding of the1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the2-1-(1)^(th) sub-message, and the 3-1-(i−1)^(th) sub-message from thetransmission message in the (i−1)^(th) time slot.

The method may further include that the allocating allocates thetransmission power B to the 2-1-(i)^(th) sub-message to enable areceiver of the adjacent transmission/reception pair to succeed indecoding of the 2-1-(1)^(th) sub-message from the transmission messagein the (i)^(th) time slot.

In another general aspect, there is provided a communication method of areceiver corresponding to a second transmitter, the method comprising:receiving a 1-1-(i−1)^(th) sub-message and a 2-1-(i−1)^(th) sub-messagefrom among the 1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th)sub-message, a 2-1-(i)^(th) sub-message, and a 3-1-(i−1)^(th)sub-message transmitted from a first transmitter based on differenttransmission powers in a (i−1)^(th) time slot; receiving a1-2-(i−1)^(th) sub-message, a 2-2-(i−1)^(th) sub-message, a 2-2-(i)^(th)sub-message, and a 3-2-(i−1)^(th) sub-message transmitted from thesecond transmitter based on different transmission powers in the(i−1)^(th) time slot; decoding the 1-2-(i−1)^(th) sub-message and the2-2-(i−1)^(th) sub-message; eliminating the 1-2-(i−1)^(th) sub-messageand the 2-2-(i−1)^(th) sub-message from the received sub-messages; andproviding, to a receiver corresponding to the first transmitter, the1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the2-2-(i)^(th) sub-message and the 3-2-(i−1)^(th) sub-message.

The method may further include: estimating an interference channelbetween the first transmitter and the receiver corresponding to thesecond transmitter; and reporting information associated with theinterference channel to at least one of the first transmitter and thesecond transmitter.

The method may further include that the providing performs: adjusting atime synchronization or a phase synchronization of each of the1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the2-2-(i)^(th) sub-message, and the 3-2-(i−1)^(th) sub-message; andproviding, as an analog signal, the 1-1-(i−1)^(th) sub-message, the2-1-(i−1)^(th) sub-message, the 2-2-(i)^(th) sub-message, and the3-2-(i−1)^(th) sub-message, to the receiver corresponding to the firsttransmitter.

The method may further include that: transmission powers of the1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the2-1-(i)^(th) sub-message, and the 3-1-(i−1)^(th) sub-message transmittedin the (i−1)^(th) time slot are transmission powers A, B, C, and D [W],respectively; A, B, C, and D denote real numbers; and A>B>C>D.

In another general aspect, there is provided a communication method of areceiver corresponding to a first transmitter, the method comprising:distinguishing a 1-1-(i−1)^(th) sub-message, a 2-1-(i−1)^(th)sub-message, and a 2-2-(i)^(th) sub-message from among the1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the2-2-(i)^(th) sub-message, and a 3-2-(i−1)^(th) sub-message transmittedfrom a receiver corresponding to a second transmitter, in response to:the first transmitter transmitting the 1-1-(i−1)^(th) sub-message, the2-1-(i−1)^(th) sub-message, the 2-1-(i)^(th) sub-message, and a3-1-(i−1)^(th) sub-message; and the second transmitter transmitting the1-2-(i−1)^(th) sub-message, the 2-2-(i−1)^(th) sub-message, the2-2-(i)^(th) sub-message, and a 3-2-(i−1)^(th) sub-message in an(i−1)^(th) time slot; receiving a 1-1-(i)^(th) sub-message, the2-1-(i)^(th) sub-message, a 2-1-(i+1)^(th) sub-message, and a3-1-(i)^(th) sub-message from the first transmitter in an (i)^(th) timeslot; receiving a 1-2-(i)^(th) sub-message, and the 2-2-(i)^(th)sub-message from the second transmitter in the (i)^(th) time slot; andextracting the 1-1-(i)^(th) sub-message, the 2-1-(i)^(th) sub-message,and the 3-1-(i)^(th) sub-message from the sub-messages received in the(i)^(th) time slot, using the 1-2-(i)^(th) sub-message and the2-2-(i)^(th) sub-message received from the receiver corresponding to thesecond transmitter.

The method may further include that the extracting performs: extractingthe 1-1-(i)^(th) sub-message and the 2-1-(i)^(th) sub-message based on atransmission power of each of the sub-messages received in the (i)^(th)time slot; and eliminating the 1-2-(i)^(th) sub-message from remainingsub-messages, excluding the 1-1-(i)^(th) sub-message and the2-1-(i)^(th) sub-message among the sub-messages received in the (i)^(th)time slot.

The method may further include that the extracting sequentiallyeliminates the 2-1-(i+1)^(th) sub-message and the 1-2-(i)^(th)sub-message to extract the 3-1-(i)^(th) sub-message, after the1-2-(i)^(th) sub-message is eliminated from the remaining sub-messages.

A non-transitory computer-readable recording medium may store a programimplementing any of the above methods.

Other features and aspects may be apparent from the followingdescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a communication systemincluding two transmission/reception pairs.

FIG. 2 is a diagram illustrating an example of a channel modelassociated with two transmission/reception pairs.

FIG. 3 is a diagram illustrating a plurality of sources that transmitsub-messages.

FIG. 4 is a diagram illustrating an example of a plurality ofdestinations that receive sub-messages transmitted from a plurality ofsources.

FIG. 5 is a diagram illustrating an example of a destination thatremoves a sub-message.

FIG. 6 is a diagram illustrating another example of a destination thatremoves a sub-message.

FIG. 7 is a diagram illustrating another example of a plurality ofsources that transmit sub-messages.

FIG. 8 is a diagram illustrating another example of a destination thatremoves a sub-message.

FIG. 9 is a diagram illustrating another example of a destination thatremoves a sub-message.

FIG. 10 is a diagram illustrating an example of a destination thatprovides several sub-messages to another destination.

FIG. 11 is a diagram illustrating an example of a destination thatremoves a sub-message using sub-messages received from anotherdestination.

FIG. 12 is a diagram illustrating an example of sub-messages remainingin a destination after a sub-message is removed.

FIG. 13 is a diagram illustrating an example of a destination thatreceives an additional sub-message.

FIG. 14 is a diagram illustrating an example of a destination thateliminates a sub-message having an amplified power.

FIG. 15 is a diagram illustrating another example of a destination thatremoves a sub-message.

FIG. 16 is a flowchart illustrating an example method of interactionbetween a plurality of sources and a plurality of destinations.

Throughout the drawings and the description, unless otherwise described,the same drawing reference numerals should be understood to refer to thesame elements, features, and structures. The relative size and depictionof these elements may be exaggerated for clarity, illustration, andconvenience.

DETAILED DESCRIPTION

The following description is provided to assist the reader in gaining ato comprehensive understanding of the methods, apparatuses, and/orsystems described herein. Accordingly, various changes, modifications,and equivalents of the methods, apparatuses, and/or systems describedherein may be suggested to those of ordinary skill in the art. Theprogression of processing steps and/or operations described is anexample; however, the sequence of steps and/or operations is not limitedto that set forth herein and may be changed as is known in the art, withthe exception of steps and/or operations necessarily occurring in acertain order. Also, descriptions of well-known functions andconstructions may be omitted for increased clarity and conciseness.

FIG. 1 illustrates an example of a communication system including twotransmission/reception pairs.

Referring to an example 110, each of two base stations (BS1 and BS2)acts as a transmitter in a downlink communication, and each of twoterminals (MS1 and MS2) acts as a receiver. In this example, a signaltransmitted from the BS1 may act as an interference to the MS2, and asignal transmitted from the BS2 may act as an interference to the MS1.

Referring to an example 120, each of two terminals (MS1 and MS2) acts asa transmitter, and each of two base stations (BS1 and BS2) may act as areceiver. In this example, a signal transmitted from the MS1 may act asan interference to the BS2, and a signal transmitted from the MS2 mayact as an interference to the BS1.

The communication system including the two transmission/reception pairsof FIG. 1 may be expressed as a channel model in FIG. 2.

FIG. 2 illustrates an example of a channel model associated with twotransmission/reception pairs.

Referring to FIG. 2, a transmitter 1 and a receiver 1 may construct asingle transmission/reception pair and a transmitter 2 and a receiver 2may construct another single transmission/reception pair. In oneexample, a signal channel between the transmitter 1 and the receiver 1may be expressed as h₁₁, and a signal channel between the transmitter 2and the receiver 2 may be expressed as h₂₂. An interference channelbetween the transmitter 1 and the receiver 2 may be expressed as h₁₂,and an interference channel between the transmitter 2 and the receiver 1may be expressed as h₂₁. Here, a reception signal of each of thereceivers may include a desired signal, an interference signal, and anoise.

A method of transmitting/receiving may be changed based on a status ofthe interference channels h₁₂ and h₂₁. Each of the receivers may regardthe interference as a noise when a strength of an interference is weak,and the receivers may decode the reception signal. Each of the receiversmay eliminate the interference from the reception signal when thestrength of the interference is strong, and may decode the desiredsignal from the signal remaining. When the interference is moderate, aHan-Kobayashi method may be used. In one example, the Han-Kobayashimethod may not always achieve an optimal performance.

Example embodiments suggest a rate split scheme of splitting atransmission message into at least four sub-messages in a single timeslot. In one example, the at least four sub-messages included in thetransmission message in the single time slot may include a part ofsub-messages transmitted in a subsequent time slot.

FIG. 3 illustrates an example of a plurality of sources that transmitssub-messages. In this example, each of a source 1 (S1) and a source 2(S2) transmits four sub-messages in an i−1^(th) time slot.

Referring to FIG. 3, the source 1 may construct a transmission messageincluding a 1-1-(i−1)^(th) sub-message (COM1(i−1)), a 2-1-(i−1)^(th)sub-message(PRV_(A) 1(i−1)), a 2-1-(i)^(th) sub-message (PRV_(A) 1(i))and a 3-1-(i−1)^(th) sub-message (PRV_(B) 1(i−1)) in an i−1^(th) timeslot. The source 2 may construct a transmission message including a1-2-(i−1)^(th) sub-message (COM2(i−1)), a 2-2-(i−1)^(th) sub-message(PRV_(A) 2(i−1)), a 2-2-(i)^(th) sub-message (PRV_(A) 2(i)), and a3-2-(i−1)^(th) sub-message (PRV_(B) 2(i−1)) in an i−1^(th) time slot.

Here, a transmission power (or a transmission rate) of each of the1-1-(i−1)^(th) sub-message (COM1(i−1)), the 1-2-(i−1)^(th) sub-message(COM2(i−1)), the 2-1-(i−1)^(th) sub-message (PRV_(A) 1(i−1)), and the2-2-(i−1)^(th) sub-message (PRV_(A) 2(i−1)) may be set to be decoded byboth the destination 1 (D1) and the destination 2 (D2), whereas atransmission power of each of the 2-1-(i)^(th) sub-message (PRV_(A)1(i)), the 3-1-(i−1)^(th) sub-message (PRV_(B) 1(i−1)), the 2-2-(i)^(th)sub-message (PRV_(A) 2(i)), and the 3-2-(i−1)^(th) sub-message (PRV_(B)2(i−1) may be set to be decoded by only a corresponding destination.

A transmission power of each of the sub-messages may be more preciselydetermined based on a status of two interference channels. For ease ofdescription, it is presumed that a strength of each of signal channelsis a signal-to-noise ratio (SNR), a strength of each interferencechannels is SNR/2, and a strength of a direct channel between thedestination 1 and the destination 2 is SNR/4 in the descriptions ofFIGS. 3 through 15.

A transmission power of each of the 1-1-(i−1)^(th) sub-message(COM1(i−1)), the 2-1-(i−1)^(th) sub-message (PRV_(A) 1(i−1)), the2-1-(i)^(th) sub-message (PRV_(A) 1(i)) and the 3-1-(i−1)^(th)sub-message (PRV_(B) 1(i−1)) may be set to be different from each other.In the same manner, a transmission power of each of the 1-2-(i−1)^(th)sub-message (COM2(i−1)), the 2-2-(i−1)^(th) sub-message (PRV_(A)2(i−1)), the 2-2-(i)^(th) sub-message (PRV_(A) 2(i)) and the 3-2-(i−1)thsub-message (PRV_(B) 2(i−1)) may also be set to be different from eachother. For example, when A, B, C, and D are real numbers, and A>B>C>D,transmission powers of the 1-1-(i−1)^(th) sub-message (COM1(i−1)), the2-1-(i−1)^(th) sub-message (PRV_(A) 1(i−1)), the 2-1-(i)^(th)sub-message (PRV_(A)l(i)) and the 3-1-(i−1)^(th) sub-message (PRV_(B)1(i−1)) may be A, B, C, D [W], respectively, and transmission powers ofthe 1-2-(i−1)^(th) sub-message (COM2(i−1)), the 2-2-(i−1)^(th)sub-message (PRV_(A) 2(i−1)), the 2-2-(i)^(th) sub-message (PRV_(A)2(i)) and the 3-2-(i−1)^(th) sub-message (PRV_(B) 2(i−1)) may also be A,B, C, D [W], respectively.

In FIGS. 3 through 15, it is presumed that transmission powers of the1-1-(i−1)^(th) sub-message (COM1(i−1)), the 2-1-(i−1)^(th) sub-message(PRV_(A) 1(i−1)), the 2-1-(i)^(th) sub-message (PRV_(A) 1(i)), and the3-1-(i−1)^(th) sub-message (PRV_(B) 1(i−1)) may be SNR, 3SNR/4, SNR/2,SNR/4, respectively, and transmission powers of the 1-2-(i−1)^(th)sub-message (COM2(i−1)), the 2-2-(i−1)^(th) sub-message (PRV_(A)2(i−1)), the 2-2-(i)^(th) sub-message (PRV_(A) 2(i)), and 3-2-(i−1)^(th)sub-message (PRV_(B) 2(i−1)) may be SNR, 3SNR/4, SNR/2, SNR/4,respectively.

When the strength of each of the channels and the transmission power ofeach of the sub-messages are presumed as described above, each of thedestination 1 and the destination 2 may receive six sub-messages asillustrated in FIG. 4.

FIG. 4 illustrates an example of a plurality of destinations thatreceive sub-messages transmitted from a plurality of sources. In thisexample, destination 1 and destination 2 receive sub-messagestransmitted from each of the source 1 and the source 2 in an i−1^(th)time slot.

Referring to FIG. 4, each of the destination 1 and the destination 2 mayreceive six sub-messages from the source 1 and the source 2 in thei−1^(th) time slot.

A strength of a channel between the destination 1 and the source 1 isSNR, and thus, the destination 1 may receive four sub-messages from thesource 1. A strength of an interference channel between the destination1 and the source 2 is SNR/2. Thus, the destination 1 may only receive a1-2-(i−1)^(th) sub-message (COM2(i−1)) and a 2-2-(i−1)^(th) sub-message(PRV_(A) 2(i−1)) from the source 2. A reception power of the destination2 for a 2-2-(i)^(th) sub-message (PRV_(A) 2(i)) and a 3-2-(i−1)^(th)sub-message (PRV_(B) 2(i−1)) transmitted from the source 2 may decreaseto a noise level, and thus, the 2-2-(i)^(th) sub-message (PRV_(A) 2(i))and the 3-2-(i−1)^(th) sub-message (PRV_(B) 2(i−1)) may be regarded as apart of a noise.

A strength of a channel between the destination 2 and the source 2 isSNR, and thus, the destination 2 may receive all four sub-messages fromthe source 2, and a strength of an interference channel between thedestination 2 and the source 1 is SNR/2. Thus, the destination 2 mayonly receive a 1-1-(i−1)^(th) sub-message (COM1(i−1)), a 2-1-(i−1)^(th)sub-message (PRV_(A) 1(i−1)) from the source 1. In one example, areception power for a 2-1-(i)^(th) sub-message (PRV_(A)l(i)) and a3-1-(i−1)^(th) sub-message (PRV_(B) 1(i−1)) transmitted from the source1 may be decreased to a noise level, and thus, the 2-1-(i)^(th)sub-message (PRV_(A) 1(i)) and the 3-1-(i−1)^(th) sub-message (PRV_(B)1(i−1)) may be regarded as a part of a noise.

A procedure where the source 2 processes received sub-messages will bedescribed in detail with reference to FIGS. 5 and 6. The source 1 mayperform in the same manner as the source 2.

FIG. 5 illustrates an example of a destination that removes asub-message. In this example, destination 2 removes a sub-messageCOM1(i−1) in an i−1^(th) time slot.

Referring to FIG. 5, the destination 2 may decode a 1-2-(i−1)^(th)sub-message (COM2(i−1)) having a highest power among received sixsub-messages in the i−1^(th) time slot. The destination 2 may identifythe 1-2-(i−1)^(th) sub-message (COM2(i−1)) having the highest poweramong the received six sub-messages, and may decode the 1-2-(i−1)^(th)sub-message (COM2(i−1)) first. In one example, the destination 2 mayregard remaining five sub-messages as a noise.

When the 1-2-(i−1)^(th) sub-message (COM2(i−1)) is eliminated from thesix sub-messages after the 1-2-(i−1)^(th) sub-message (COM2(i−1)) isdecoded, only five sub-messages remain in the destination 2 asillustrated in FIG. 5.

FIG. 6 illustrates another example of a destination that removes asub-message. In this example, destination 2 removes a sub-messagePRV_(A)2(i−1) in an i−1^(th) time slot.

Referring to FIG. 6, the destination 2 may decode a 2-2-(i−1)^(th)sub-message (PRV_(A) 2(i−1)) having a highest power among remaining fivesub-messages in the i−1^(th) time slot. In one example, the destination2 may decode the 2-2-(i−1)^(th) sub-message (PRV_(A) 2(i−1)) whileregarding remaining four sub-messages as a noise, and may eliminate the2-2-(i−1)^(th) sub-message (PRV_(A) 2(i−1)).

When the 2-2-(i−1)^(th) sub-message (PRV_(A) 2(i−1)) is eliminated, onlyfour sub-messages remain in the destination 2.

Although not illustrated in FIG. 6, the destination 1 may alsosequentially decode and eliminate two sub-messages and only foursub-messages may remain in the destination 1.

FIG. 7 illustrates another example of a plurality of sources thattransmit sub-messages. In this example, each of a source 1 and a source2 transmits four sub-messages in an i−1^(th) time slot.

Referring to FIG. 7, the source 1 may transmit a 1-1-(i)^(th)sub-message (COM1(i)), a 2-1-(i)^(th) sub-message (PRV_(A) 1(i)), a2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)), and a 3-1-(i)^(th)sub-message (PRV_(B) 1(i)) in an i^(th) time slot, and a source 2 maytransmit a 1-2-(i)^(th) sub-message (COM2(i)), a 2-2-(i)^(th)sub-message (PRV_(A) 2(i)), a 2-1-(i+1)^(th) sub-message (PRV_(A)2(i+1)) and a 3-1-(i)^(th) sub-message (PRV_(B) 2(i)) in the i^(th) timeslot. In one example, the 2-1-(i)^(th) sub-message (PRV_(A) 1(i)) may beidentical to a sub-message that is transmitted by the source 1 at atransmission power of SNR/2 in an i−1^(th) time slot, and the2-2-(i)^(th) sub-message (PRV_(A) 2(i)) may also be identical to asub-message that is transmitted by the source 2 at the transmissionpower of SNR/2 in the i−1^(th) time slot.

Each of a destination 1 and a destination 2 may receive six sub-messagesin the same manner as in the i−1^(th) time slot. A procedure where thedestination 1 receives six sub-messages will be further described withreference to FIG. 7.

A strength of a channel between the destination 1 and the source 1 isSNR, and thus, the destination 1 may receive all the 1-1-(i)^(th)sub-message (COM1(i)), the 2-1-(i)^(th) sub-message (PRV_(A) 1(i)), the2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)), and the 3-1-(i)^(th)sub-message (PRV_(B) 1(i)) from the source 1.

A strength of the channel between the destination 1 and the source 2 isSNR/2, and thus, the destination 1 may only receive the 1-2-(i)^(th)sub-message (COM2(i)) and the 2-2-(i)^(th) sub-message (PRV_(A) 2(i))from the source 2. A reception power of the 2-1-(i+1)^(th) sub-message(PRV_(A) 2(i+1)) and the 3-1-(i)^(th) sub-message (PRV_(B) 2(i)) may bedecrease to a noise level.

FIG. 8 illustrates another example of a destination that removes asub-message. In this example, destination 1 removes a sub-messageCOM1(i) in an i^(th) time slot.

Referring to FIG. 8, the destination 1 may decode a 1-1-(i)^(th)sub-message (COM1(i)) having a highest power among six sub-messagereceived from the source 1 and the source 2 in the i^(th) time slot. Inone example, the destination 1 may decode the 1-1-(i)^(th) sub-message(COM1(i)) while regarding remaining five sub-messages as a noise, andmay eliminate the 1-1-(i)^(th) sub-message (COM1(i)).

When the 1-1-(i)^(th) sub-message (COM1(i)) is eliminated, only fivesub-messages remain in the destination 1.

FIG. 9 illustrates another example of a destination that removes asub-message. In this example, destination 1 removes a sub-messagePRV_(A) 1(i) in an i^(th) time slot.

Referring to FIG. 9, the destination 1 may decode a 2-1-(i)^(th)sub-message (PRV_(A) 1(i)) having a highest power among remaining fivesub-messages in the i^(th) time slot. In one example, the destination 1may decode the 2-1-(i)^(th) sub-message (PRV_(A) 1(i)) while regardingremaining four sub-messages as a noise, and may eliminate the2-1-(i)^(th) sub-message (PRV_(A)(i)).

When the 2-1-(i)^(th) sub-message (PRV_(A) 1(i)) is eliminated, only thefour sub-messages remain in the destination 1.

FIG. 10 illustrates an example of a destination that provides severalsub-messages to another destination. In this example, destination 2provides several sub-messages to destination 1 in an i^(th) time slot.

Referring to FIG. 10, the destination 2 may provide, to the destination1, remaining four sub-messages after being received in the i−1^(th) timeslot. In one example, the four sub-messages may be combined together andmay be transmitted in a form of an analog signal. For example, thedestination 2 may accurately adjust a time synchronization and a phasesynchronization of the four sub-messages to enable the destination 1 toeffectively perform an analog-elimination, and may provide the foursub-messages to the destination 1.

In one example, a 3-2-(i−1)^(th) sub-message (PRV_(B) 2(i−1)) and a2-1-(i−1)^(th) sub-message (PRV_(A) 1(i−1)) having a weak power may beregarded as a noise in the destination 1 due to a path loss between thedestination 1 and the destination 2 while the four sub-messages aretransmitted to the destination 1. Accordingly, the destination 1 mayonly receive a 2-2-(i)^(th) sub-message (PRV_(A) 2(i)) and a1-1-(i−1)^(th) sub-message (COM1(i−1)).

FIG. 11 illustrates that a destination 1 eliminates a sub-messagePRV_(A) 2(i) using sub-messages received from destination 2 in an i^(th)time slot.

Referring to FIG. 11, the destination 1 eliminates a 2-2-(i)^(th)sub-message (PRV_(A) 2(i)) from remaining four sub-messages usingsub-messages provided by the destination 1. In one example, thedestination 1 may already know a 1-1-(i−1)^(th) sub-message (COM1(i−1))received in an i−1 ^(th) time slot. Accordingly, the destination 1 maysum the remaining four messages and the 1-1-(i−1)^(th) sub-message(COM1(i−1)) and may subtract the two sub-messages received from thedestination 1, eliminating the 2-2-(i)^(th) sub-message (PRV_(A) 2(i))from the remaining four sub-messages.

Therefore, three sub-messages may only remain in the destination 1. Forexample, a 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)), a 3-1-(i)^(th)sub-message (PRV_(B) 1(i)), and a 1-2-(i)^(th) sub-message (COM2(i)) mayonly remain in the destination 1.

FIG. 12 illustrates sub-messages remaining in a destination 1 after asub-message PRV_(A) 2(i) is eliminated in an i^(th) time slot.

Referring to FIG. 12, a 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)), a3-1-(i)^(th) sub-message (PRV_(B) 1(i)), and a 1-2-(i)^(th) sub-message(COM2(i)) may only remain in the destination 1 in the i^(th) time slot.In one example, a power of the 2-1-(i+1)^(th) sub-message (PRV_(A)1(i+1)) and a power of the 1-2-(i)^(th) sub-message (COM2(i)) areidentical or are sufficiently identical, and thus, the destination 1 maynot decode one of the 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)) andthe 1-2-(i)^(th) sub-message (COM2(i)).

FIG. 13 illustrates that a destination 1 additionally receives asub-message PRV_(A) 1(i+1) in an i+1^(th) time slot.

Referring to FIG. 13, a source 1 may transmit a 1-1-(i+1)^(th)sub-message (COM1(i+1)), a 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)),a 2-1-(i+2)^(th) sub-message (PRV_(A) 1(i+2)), and a 3-1-(i+1)^(th)sub-message (PRV_(B) 1(i+1)) in an i+1^(th) time slot, and a source 2may transmit a 1-2-(i+1)^(th) sub-message (COM2(i+1)), a 2-2-(i+1)^(th)sub-message (PRV_(A) 2(i+1)), a 2-1-(i+2)^(th) sub-message (PRV_(A)2(i+2)), and a 3-1-(i+1)^(th) sub-message (PRV_(B) 2(i+1)) in thei+1^(th) time slot. In one example, the 2-1-(i+1)^(th) sub-message(PRV_(A) 1(i+1)) is identical to a sub-message that is transmitted bythe source 1 at a transmission power of SNR/2 in an i^(th) time slot,and the 2-2-(i+1)^(th) sub-message (PRV_(A) 2(i+1)) is identical to asub-message that is transmitted by the source 2 at a transmission powerof SNR/2 in the i^(th) time slot.

In one example, the destination 1 may decode the 1-1-(i+1)^(th)sub-message (COM1(i+1)) and the 2-1-(i+1)^(th) sub-message (PRV_(A)1(i+1)), and thus, the 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1))received in the i+1^(th) time slot and the remaining 2-1-(i+1)^(th)sub-message (PRV_(A) 1(i+1)) of FIG. 12 may be combined. Accordingly, apower of the 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)) may beamplified as illustrated in FIG. 13.

Therefore, the destination 1 may have sub-messages having differentpowers.

FIG. 14 illustrates that a destination 1 eliminates a PRV_(A) 1(i+1)having an amplified power.

Referring to FIG. 14, the destination 1 may decode a 2-1-(i+1)^(th)sub-message (PRV_(A) 1(i+1)) having a strongest power among threesub-messages and may eliminate the decoded 2-1-(i+1)^(th) sub-message(PRV_(A) 1(i+1)). Accordingly, only two sub-messages having differentpowers may remain in the destination 1.

For example, only a 3-1-(i)^(th) sub-message (PRV_(B) 1(i)) and a1-2-(i)^(th) sub-message (COM2(i)) may remain in the destination 1,after the 2-1-(i+1)^(th) sub-message (PRV_(A) 1(i+1)) is eliminated.

FIG. 15 illustrates that a destination 1 eliminates a COM2(i) in ani+1^(th) time slot.

Referring to FIG. 15, the destination 1 may decode a 1-2-(i)^(th)sub-message (COM2(i)) having a stronger power among a 3-1-(i)^(th)sub-message (PRV_(B) 1(i)) and the 1-2-(i)^(th) sub-message (COM2(i)),and eliminated the decoded 1-2-(i)^(th) sub-message (COM2(i)).Accordingly, only the 3-1-(i)^(th) sub-message (PRV_(B) 1(i)) may remainin the destination 1.

Accordingly, the destination 1 may decode all desired sub-messages.

FIG. 16 illustrates operation methods of a source 1, a source 2, adestination 1, and a destination 2.

Referring to FIGS. 2 through 16, each of the source 1 and the source 2may recognize channel information prior to transmitting a message. Thesource 1 may request the destination 1 to estimate h₁₁ to recognize astrength of h₁₁. In one example, the destination 1 may feed back SNR1 tothe source 1 after measuring SNR1, e.g., a strength of h₁₁. Also, thesource 2 may request the destination 2 to estimate h₂₂, and thedestination 2 may feed back SNR2 to the source 2 after measuring SNR2,e.g., a strength of h₂₂.

The source 1 may request the destination 2 to estimate an interferencechannel h₁₂, and the destination 2 may feed back, to the source 2,interference to Noise Ratio (INR2), e.g., a strength of the interferencechannel h₁₂, after measuring the INR2. The source 1 may also request thedestination 1 to estimate an interference channel h₂₁, and thedestination 1 may feed back INR1, e.g., a strength of the interferencechannel h₂₁, to the source 1 after measuring the INR1. Then, the source1 and the source 2 may share INR1 and the INR2 with each other.

Also, the destination 1 and the destination 2 may request estimation ofa channel between the destination 1 and the destination 2. Thedestination 1 and the destination 2 may may share information associatedwith a strength of the channel.

Each of sources may construct a transmission message including foursub-messages after the sources and the destinations finish measuring orexchanging information associated with channels.

For example, the source 1 may transmit a 1-1-(i)^(th) sub-message(COM1(i)), a 2-1-(i)^(th) sub-message (PRV_(A) 1(i)), a 2-1-(i+1)^(th)sub-message(PRV_(A) 1 (i+1)), and a 3-1-(i)^(th) sub-message (PRV_(B)1(i)), and the source 2 may transmit a 1-2-(i)^(th) sub-message(COM2(i)), a 2-2-(i)^(th) sub-message (PRV_(A) 2(i)), a 2-1-(i+1)^(th)sub-message (PRV_(A) 2(i+1)), and a 3-1-(i)^(th) sub-message (PRV_(B)2(i)).

In one example, two sub-messages among the four sub-messages transmittedfrom the source 1 may act as interferences in the destination 2, and twosub-messages among the four sub-messages transmitted from the source 2may act as interferences in the destination 1.

The destination 1 may decode two sub-messages having a strongest poweramong received six sub-messages, e.g., the 1-1-(i)^(th) sub-message(COM1(i)) and the 2-1-(i)^(th) sub-message (PRV_(A) 1(i)), and mayeliminate the 1-1-(i)^(th) sub-message (COM1(i)) and the 2-1-(i)^(th)sub-message (PRV_(A) 1(i)). The destination 2 may also decode twosub-messages having a strongest power among received six sub-messages,e.g., the 1-2-(i)^(th) sub-message (COM2(i)) and the 2-2-(i)^(th)sub-message (PRV_(A) 2(i)), and may eliminate the 1-2-(i)^(th)sub-message (COM2(i)) and the 2-2-(i)^(th) sub-message (PRV_(A) 2(i)).

Each of the destination 1 and the destination 2 may share remainingsub-messages. The destination 1 may provide the remaining foursub-messages to the destination 2, and the destination 2 may provide theremaining four sub-messages to the destination 1.

The destination 1 may eliminate the interferences using sub-messagesprovided by the destination 2, and the destination 2 may eliminate theinterferences using sub-messages provided by the destination 1.

Accordingly, the destination 1 may decode the 2-1-(i+1)^(th) sub-message(PRV_(A) 1(i+1)) and the 3-1-(i)^(th) sub-message (PRV_(B) 1(i)), andthe destination 2 may decode the 2-1-(i+1)^(th) sub-message (PRV_(A)2(i+1)) and the 3-1-(i)^(th) sub-message (PRV_(B) 2(i)).

Therefore, the destination 1 and the destination 2 may decode alldesired sub-messages.

The method according to the above-described example embodiments may berecorded in computer-readable media including program instructions toimplement various operations embodied by a computer. The media may alsoinclude, alone or in combination with the program instructions, datafiles, data structures, and the like. Examples of computer-readablemedia include magnetic media such as hard disks, floppy disks, andmagnetic tape; optical media such as CD-ROM disks and DVDs;magneto-optical media such as optical disks; and hardware devices thatare specially configured to store and perform program instructions, suchas read-only memory (ROM), random access memory (RAM), flash memory, andthe like. Examples of program instructions include both machine code,such as produced by a compiler, and files containing higher level codethat may be executed by the computer using an interpreter. The describedhardware devices may be configured to act as one or more softwaremodules in order to perform the operations of the above-describedexample embodiments, or vice versa. In addition, a computer-readablestorage medium may be distributed among computer systems connectedthrough a network and computer-readable codes or program instructionsmay be stored and executed in a decentralized manner.

A number of exemplary embodiments have been described above.Nevertheless, it will be understood that various modifications may bemade. For example, suitable results may be achieved if the describedtechniques are performed in a different order and/or if components in adescribed system, architecture, device, or circuit are combined in adifferent manner and/or replaced or supplemented by other components ortheir equivalents. Accordingly, other implementations are within thescope of the following claims.

What is claimed is:
 1. A communication method of a receivercorresponding to a second transmitter, the method comprising: receivinga 1-1-(i−1)^(th) sub-message and a 2-1-(i−1)^(th) sub-message from amongthe 1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, a 2-1-(i)^(th) sub-message, and a 3-1-(i−1)^(th) sub-message transmitted froma first transmitter based on different transmission powers in a(i−1)^(th) time slot; receiving a 1-2-(i−1)^(th) sub-message, a2-2-(i−1)^(th) sub-message, a 2-2-(i)^(th) sub-message, and a3-2-(i−1)^(th) sub-message transmitted from the second transmitter basedon different transmission powers in the (i−1)^(th) time slot; decodingthe 1-2-(i−1)^(th) sub-message and the 2-2-(i−1)^(th) sub-message;eliminating the 1-2-(i−1)^(th) sub-message and the 2-2-(i−1)^(th)sub-message from the received sub-messages; and providing, to a receivercorresponding to the first transmitter, the 1-1-(i−1)^(th) sub-message,the 2-1-(i−1)^(th) sub-message, the 2-2-(i)^(th) sub-message and the3-2-(i−1)^(th) sub-message.
 2. The method of claim 1, furthercomprising: estimating an interference channel between the firsttransmitter and the receiver corresponding to the second transmitter;and reporting information associated with the interference channel to atleast one of the first transmitter and the second transmitter.
 3. Themethod of claim 1, wherein the providing performs: adjusting a timesynchronization or a phase synchronization of each of the 1-1-(i−1)^(th)sub-message, the 2-1-(i−1)^(th) sub-message, the 2-2-(i)^(th)sub-message, and the 3-2-(i−1)^(th) sub-message; and providing, as ananalog signal, the 1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th)sub-message, the 2-2-(i)^(th) sub-message, and the 3-2-(i−1)^(th)sub-message, to the receiver corresponding to the first transmitter. 4.The method of claim 1, wherein: transmission powers of the1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the 2-1-(i)^(th) sub-message, and the 3-1-(i−1)^(th) sub-message transmitted inthe (i−1)^(th) time slot are transmission powers A, B, C, and D [W],respectively; A, B, C, and D denote real numbers; and A>B>C>D.
 5. Acommunication method of a receiver corresponding to a first transmitter,the method comprising: distinguishing a 1-1-(i−1)^(th) sub-message, a2-1-(i−1)^(th) sub-message, and a 2-2-(i)^(th) sub-message from amongthe 1-1-(i−1)^(th) sub-message, the 2-1-(i−1)^(th) sub-message, the2-2-(i)^(th) sub-message, and a 3-2-(i−1)^(th) sub-message transmittedfrom a receiver corresponding to a second transmitter, in response to:the first transmitter transmitting the 1-1-(i−1)^(th) sub-message, the2-1-(i−1)^(th) sub-message, the 2-1-(i)^(th) sub-message, and a3-1-(i−1)^(th) sub-message; and the second transmitter transmitting the1-2-(i−1)^(th) sub-message, the 2-2-(i−1)^(th) sub-message, the2-2-(i)^(th) sub-message, and a 3-2-(i−1)^(th) sub-message in an(i−1)^(th) time slot; receiving a 1-1-(i)^(th) sub-message, the2-1-(i)^(th) sub-message, a 2-1-(i+1)^(th) sub-message, and a3-1-(i)^(th) sub-message from the first transmitter in an (i)^(th) timeslot; receiving a 1-2-(i)^(th) sub-message, and the 2-2-(i)^(th)sub-message from the second transmitter in the (i)^(th) time slot; andextracting the 1-1-(i)^(th) sub-message, the 2-1-(i)^(th) sub-message,and the 3-1 -(i)^(th) sub-message from the sub-messages received in the(i)^(th) time slot, using the 1-2-(i)^(th) sub-message and the2-2-(i)^(th) sub-message received from the receiver corresponding to thesecond transmitter.
 6. The method of claim 5, wherein the extractingperforms: extracting the 1-1-(i)^(th) sub-message and the 2-1-(i)^(th)sub-message based on a transmission power of each of the sub-messagesreceived in the (i)^(th) time slot; and eliminating the 1-2-(i)^(th)sub-message from remaining sub-messages, excluding the 1-1-(i)^(th)sub-message and the 2-1-(i)^(th) sub-message among the sub-messagesreceived in the (i)^(th) time slot.
 7. The method of claim 6, whereinthe extracting sequentially eliminates the 2-1-(i+1)^(th) sub-messageand the 1-2-(i)^(th) sub-message to extract the 3-1-(i)^(th)sub-message, after the 1-2-(i)^(th) sub-message is eliminated from theremaining sub-messages.